Thursday, May 22, 2008

Understanding root causes

PELLSTON, Mich. - Chain saws scream in a northern Michigan forest, but it's not the familiar sound of lumberjacks.

This time the tree killers are environmental researchers. They hope that years from now the aspens they remove will be replaced with a healthy mix of maples, oaks, beeches and pines — which should soak up more carbon dioxide from an ever warmer world.

They say the experiment is the first they're aware of that involves removing large numbers of trees to promote growth of other species that will boost carbon absorption. It comes as governments and businesses around the world look for economically feasible ways to limit climate change.

It is fall now ... the aspens will already be turning. They turn in clusters, because their roots connect them.

However, there is another aspect of the aspen arborcide:

Scientists believe a diverse woodland will hold more carbon because it will be richer in nitrogen and use sunlight more efficiently. Both are key factors in photosynthesis, during which carbon is absorbed...

Yes. Celebrate Diversity!

However, no matter the wisdom of these efforts in combating climate change and celebrating diversity by increasing the carbon sequestration of the woodland, one question remains. Why make the aspens suffer such a slow, painful death?

Cutting down the aspens would cause new sprouts to multiply, so scientists instead use a technique called "girdling," in which they strip a band of bark from around each tree. It starves the trees by preventing sugars produced by the leaves from traveling to the roots.

In recent weeks, crews have girdled more than 6,700 trees — mostly aspens, with some birches — near one of the measuring towers. They should die in a year or two, allowing other species to flourish.

Oh, so aspens are like terrorists – if you kill one, you only make more. So the scientists subject the aspens to brutal torture in order to discourage other aspens from replacing them.

Some argue that those responsible for this approach have manipulated the intelligence:

Skeptics question forests' long-term reliability for sequestering carbon. They can be cut down, burned or destroyed by disease or insects. Also, it's hard to measure their storage capacity, said Jonathan Pershing, climate and energy program director for the World Resources Institute.

"Are you so sure you can tell us how much carbon is saved from your tree? That's the kind of question that makes people dubious about forest management" as a tool for limiting greenhouse gases, Pershing said.

Forest ecologists lied, aspens died!

And some of the scientists involved understand the tradeoffs involved:

"I have little pangs now and then about what we've done ... even though it's for a good reason," Vogel said. But some of the aspens and birches were already dying, and it was just a matter of time for the others, he said.